1. Field of the Invention
The present invention relates to ceramic fiber panels for the construction of portable high temperature chambers and, more particularly, to a method and apparatus for the building of portable high temperature chambers, furnaces and kilns which does not rely upon furnace walls for attachment and support but rather forms its own roof and walls when fastened or clamped together.
2. Description of the Prior Art
Heat treating furnaces, ceramic kilns, brick kilns, and the like were initially lined with dense fireclay brick since it was the only material available that would readily withstand the high heats, in excess of 2,000.degree. F., generated in such furnaces. When insulating fire brick was developed in the 1930's, it replaced fireclay brick as the lining for furnaces to take advantage of the lighter weight and lower thermal conductivity of this material. In the 1960's, insulating fire brick was largely replaced with a ceramic fiber material made of alumina-silica fibers matted into a blanket form. Such blankets are formed in a variety of widths and thicknesses and sold in long rolls. Ceramic fibers in blanket form are marketed under the trade names Kaowool by Babcock and Wilcox Company, Cerablanket or Cerafelt by Johns-Mansville Company and Durablanket or Fiberfrax by Carborundum Corporation.
Compared to brick, ceramic fiber provides twice the sound and heat capabilities of insulating fire brick and four times the heat and sound insulating capabilities of hard brick, at one-tenth the weight. It also will not retain or absorb heat and has better shock characteristics. Besides reducing the amount of fuel required to fire a furnace using a ceramic fiber blanket, the lower heat storage means that the furnace can be brought up to temperature faster and cooled faster. This allows faster cycling and quicker access to a kiln if it must be brought down for repairs.
Conventionally, since ceramic fiber comes in rolls, it is applied to the furnace ceiling and walls as a blanket, in multiple layers, by impaling upon metal studs welded in a precise pattern to the furnace walls. Unfortunately, these studs limit the temperature range of the furnace since they can withstand much less heat than the ceramic fiber material itself. Furthermore, the method of manufacture of the fiber blankets positions the individual fiber strands in parallel planes and the above method positions these parallel planes parallel to the walls of the furnace. In use, the high heat in the furnace causes shrinkage of the strands and this opens gaps at the ends of the blankets, which gaps must be periodically repacked after regular periods of use.
To overcome the above problems, it has been proposed to cut the ceramic fiber into strips and to position a plurality of strips in side-by-side, parallel relationship to form a module. The individual ceramic fiber strips are typically impaled upon stainless wire or steel rods thereby encapsulating the entire unit against a steel shell. For examples of this later construction, reference should be had to U.S. Pat. Nos. 3,819,468; 3,832,815; and 3,854,262.
While these later constructions eliminate the temperature limiting and shrinkage problems of the former method, all of the later methods require the lining to be bolted or welded to the metal furnace walls. Therefore, the procedure for building a new furnace or relining an old furnace is time consuming and expensive, requiring special tools for attaching the modules to the walls, such as the tool described in U.S. Pat. No. 3,706,870.